Lessons in Landscaping
Working with living systems like landscapes always involves an element of surprise. Sometimes the surprises are good: the perennials you planted last year came back despite an unusually harsh winter. Sometimes the surprises are not so good: drought conditions and water restrictions wipe-out thirsty perennials. Some problems develop as a result of weather events, surging pest populations or other factors beyond your control. But there are many problems that you can manage, minimize or even prevent by applying appropriate installation and management practices. Knowledge is the first step. Here are 10 common mistakes in landscaping that often lead to serious problems, and specific suggestions for preventing these problems by designing and installing landscapes that are predisposed to long-term success.
Landscape designs don't support good horticultural management practices. There are so many examples of this. Perennial beds and shrub borders have shapes and sizes that make mowing around them difficult. Trees with low limbs that extend beyond the mulch line threaten the eyeballs of those who mow near them. Narrow walkways encourage people to trample the adjacent soil, compacting it and promoting weed growth. Tall plants below utility wires force difficult pruning decisions. Plants spaced too closely make disease problems almost inevitable.
All of these problems can be solved before they even begin. Consider long-term maintenance when making every decision, from concept to design to installation to maintenance.
Not inspecting materials before introducing them into the landscape. When you're busy, you might too willingly trust that products are exactly what they're advertised to be. But in many cases, taking the time to inspect shipments can prevent serious problems. The problems can be grouped into two types: hard goods and plant materials. Among hard goods, mulch, compost and soil often contain weed seeds, disease propagules, road salt and chemical residues. Any of these can cause long-term problems. Among plant materials, root balls can contain weeds, weed seeds, disease propagules and insects. One recent example in New England is the European red ant, which has been known to colonize root balls and hitchhike to a new site, after which the colonies “bud” and spread throughout the new landscape.
Installing plants where they have no chance at thriving. We have all learned to “select plants adaptable to the site.” Yet this mistake happens repeatedly. We often blame the client, who demands a plant we know to be wrong for the site. Hold your ground; maintain your professionalism. Rather than accommodating the demand, initiate a conversation about the problem, whether it's hardiness, adaptability, long-term maintenance costs or pest susceptibility. Some clients are unbending, but many simply don't understand the issues at hand, and truly want a successful planting more than they want a specific plant. They're likely to yield to the opinion of a professional whom they trust.
Make a checklist and use it when evaluating a site. Based on each site evaluation, choose plants suited to the site's wind, temperature, soil characteristics and water availability. Choose plants that will support users' activities, including foot traffic, vehicle exhaust and urban pollution. Consider the long-term cost of pruning, mulching, weeding, irrigating, fertilizing, mowing, edging and raking leaves. Avoid plants prone to local problems: many viburnums are vulnerable to viburnum leaf beetle; true lilies are destroyed by lily leaf beetles; roses are prime hosts of Japanese beetles; plants close to playgrounds may be damaged by bicycle chains or may be otherwise vandalized; plants in parking lot islands are prone to snowplow damage, salt damage and auto impact; plants situated under building overhangs receive limited water and light, and are prone to winter ice damage; and many plants are favored by deer.
Having unrealistic expectations of the functions of plants. “Function before form” is drilled into us, whether we learn horticulture in school, from books or from a mentor. Still, plants are sometimes chosen more for their beauty than for the functions they serve in the landscape. When choosing plants, always think about function first (forming a windbreak, controlling erosion, providing a sports surface, offering habitat for wildlife, etc.). Function will determine form — size, shape, root structure, fragrance, seasonal beauty, etc.
Choosing plants that will outgrow the space provided. So much pruning could be prevented through proper plant selection. And it doesn't end there. Spacing plants too closely encourages disease development and discourages plant vigor. Oversized trees conflict with power lines and provide fodder for utility company pruning crews. Weak-wooded trees that overhang buildings become a danger to buildings and people. Trees too close to buildings cause foundation problems. Trees in containers or tree pits fail to develop extensive root systems, and eventually die from what should otherwise be minor problems.
Planting less-than-highest-quality plants incorrectly and leaving them to survive on their own. We've all learned so much in the past 20 years about the importance of selecting high-quality plants, planting them correctly and caring for them during their establishment period.
Yet we've all seen new plantings of trees and shrubs purchased at the end of a hot dry summer, showing minimal current-season growth on either shoots or roots. They're planted into holes so narrow that you wonder how they were pushed down into the ground; yet the holes were dug deep enough that the plants' crowns are buried not only under soil but also under a volcano of mulch. Alternatively, some trees and shrubs are planted so shallowly that the plastic burlap still on their root balls is clearly visible above a thin layer of dry mulch. In many cases, the plants are watered-in once and then left to survive on their own, in spite of dry spells, insect pressure and disease presence.
We have the knowledge to plant successfully. We need to apply that knowledge.
Not routinely scouting landscapes for pests and other problems. Many problems can be avoided through good plant choices. Examples include crabapples that are resistant to multiple diseases, and phlox cultivars that are resistant to powdery mildew. Other problems should be anticipated and scouted for. Learn about the plants you install. Make a list of the problems you'd most likely encounter, and the times of year you'd expect to see them. Scout the plantings at appropriate times, so that you find problems in time to treat them and before they threaten the landscape.
Allowing problems to develop unchecked, without IPM, cost or labor in mind. You can control many problems very cost-effectively and with little impact on the environment, if you detect them early and address them promptly. Those same problems, if left unchecked, can become expensive and even deadly.
Again, knowledge is the first step. After detecting a problem, learn about the options. Viburnum leaf beetle problems, for example, can be avoided completely if you choose a resistant species (or plant other genera altogether). In an established viburnum planting, you can control the problem to a large extent by late fall pruning of twigs that contain the next year's population. However, if you allow the problem to progress unchecked for just a few years, the only remaining option may be to remove the dead plant and replace it with something else.
Not advising clients on interacting with the space appropriately and respectfully. Residential landscapes are generally respected by their owners. After all, homeowners often provide input into the design process, pay the bills and feel a definite sense of ownership after the landscape is installed.
User problems are more common in public spaces, where communication is less direct or nonexistent. In some instances, communication might be difficult, but in many more instances, communication is possible. You just need to determine how to accomplish that communication.
Good landscape design “communicates” how to use spaces appropriately: curbs stop vehicles, fences create boundaries, walkways tell people where to walk. When people misuse the landscape, evaluate the situation and consider how a better design might mitigate the problem.
In addition, conversations, memos, emails, announcements and signs all have their place. If you can explain why bicycles should not be chained to tree trunks and why dogs should not be allowed to urinate on shrubs, most people will stop those activities. It helps, of course, to provide bicycle racks and dog-walking areas. If you can communicate with the users of the landscape and help them develop a sense of ownership of the space, they'll help you educate others to respect it, too.
Active learning slows down. When we perform the same tasks repeatedly in our jobs, we sense that we “know it all.” But research in plant science is very active, and new findings should influence how we create and manage landscapes. Just think about how we've changed the ways we manage pests, fertilize and mow lawns and prune large limbs.
You can learn by attending classes and workshops, consulting experts, reading on your own and talking to colleagues. Expanding your knowledge base can help you address new problems as they develop … and avoid making the common mistakes that prevent landscapes from succeeding.
Lois Berg Stack, Ph. D., is an extension specialist with the Department of Ornamental Horticulture at the University of Maine Cooperative Extension (Orono, Maine).
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